Patent GB-808703-A (GB)
Title: Improvements in or relating to type printing telegraph apparatus
IPC: B41J19/10
Filed: 1956-05-18
Abstract: 808,703. Typewriters &c. HANDLEY, J. May 10, 1957 [May 18, 1956], No. 15495/56. Class 100(4) A wire printer has a type head, a lead screw driven through a friction clutch rotation of which causes the printing head to be moved across the platen, a ratchet mounted on the lead screw, a pawl which normally engages the ratchet to prevent rotation thereof by the driving means and means for withdrawing the pawl from engagement with the ratchet to effect letter feed, spring means for advancing the pawl to meet a succeeding tooth of the ratchet, and hydraulic deceleration of ratchet and pawl by a plunger and dash pot. The rate of acceleration of the ratchet wheel may be controlled by increasing or decreasing the clutch pressure, and the rate of deceleration may be controlled by a variable leak valve in the dashpot. Uniform acceleration and deceleration of the type head during letter feed may thus be obtained. Character selection. Operation of one of relays 26, Fig. 3, selects a control plate which is moved to open the desired combination of valves in chest 5 so that impression forming sections 43 in type head 6 are pushed forward into printing position by hydraulic pressure through flexible tubes 7. Letter spacing mechanism. Punch head 6 is moved into printing position by rockers 28, Fig. 3, and 34 (not shown), which are released by one of relays 26 when energized, and rocked by cams on cam shaft 14. The impression - forming sections are not thrust out to print until head 6 has moved forwards. A further relay 26 is energized to initiate letter feed, which releases rocker 29, Fig. 1A, to be rocked by cam 36. Member 180, Fig. 3, of rocker 29 rotates shaft 54, Fig. 2, clockwise by pulling down member 181. Shaft 54 disengages pawl 15 through links 166, 167, rocker 53, from ratchet 16 which is mounted on shaft 10, thus allowing the latter to rotate clockwise, through a friction clutch, and move the type head for letter spacing. When disengaged, pawl 15 is advanced to meet the next tooth on ratchet 16 by spring 18 until collar 19 abuts dashpot 20. The next tooth of ratchet 16 pushes pawl 15, rod 172 and plunger 21 downwards until plunger 21 rests on collar 22. Plunger 21 has a non- return valve which opposes its downward but not its upward movement, thus gradually bringing ratchet 16 to rest without jarring. Leak valve 24 allows adjustment of the damping force. Ribbon feed. Anticlockwise rotation of rocker 53 about 170 turns ratchet 52 anticlockwise through pawl 51, to turn the ribbon feed rollers, through further shafts and gears, to advance the expendable ribbon an amount equal to a small fraction of a letter feed step so that the punch head passes over each portion of ribbon several times during the latters travel across the platen. Tabulation. Relay 26 releases a rocker 30 (not shown), which turns camming member 56, mounted on shaft 58, clockwise, through link 55, member 191, and shaft 58. Shaft 54 is turned by member 56 through cam 57, thus pawl 15 is disengaged from ratchet 16, lead screw 10 is allowed to turn, and the punch head traverses. Arm 57 is shaped so that it retains member 56 in operative position after relay 26 is de-energized. Type head 6 therefore continues to traverse until stopped by one of adjustable tabulation stops 59 carried on shaft 58. The impact of type head 6 on stop 59 turns shaft 58 anticlockwise releasing arm 56 from member 57 and allowing pawl 15 to re-engage ratchet 16. Type head 6 reaches its maximum speed during tabulation and is not brought to rest by the time plunger 21, Fig. 2, reaches collar 22; extra retardation is provided by a spring 25, which supports collar 22, and which is compressed and then expands again to return the parts to their normal positions. Type head return. Energization of a type head return relay 26 releases rocker 31, Fig. 3, to be rocked by a cam. Rocker 31 reverses the drive to lead screw 10 by disengaging one hydraulic clutch and engaging another, by opening and closing appropriate valves, through linkages 61, 62. The valves are held in this position even after relay 26 is de-energized by rocker 69, which, after being released to turn anticlockwise by 68 being pulled down by arm 175 rotated clockwise by shaft 67, prevents rod 68 moving upwards again. Rotation of shaft 67, Figs. 2, 3, also disengages pawl 15 from ratchet 16 through arm 212, link 203, arms 205 and 80 pivoted at 206, and rocker 53. At the end of the return run head 6 is arrested by piston 223, Fig. 1, running in damping cylinder 74<1> through arms 222 and .73 pivoted at 221. The third arm, 72, Fig. 3, moves rocker 71 and shaft 70 clockwise thus moving rocker 69 clockwise which allows rod 68 and the. clutch controlling valves to return to normal, and pawl 15 to re-engage ratchet 16. Line feed. Line feed relay 26 releases a cam operated rocker which through shaft 89, Fig. 4, arm 225, and pawl 90, disengages pawl 88 from a ratchet to allow shaft 84 to be turned through slipping clutch 83. Shaft 84 drives sprocket wheels 45, 46, Fig. 3, which feed the paper. In normal single spacing, pawl 88 engages the succeeding tooth of the ratchet wheel. For double spacing, collar 98 is moved downwards, by an eccentric pin on a handwheel, to engage pawl 88 and allow the latter to engage only every other tooth on the ratchet. A tabulating paper feed relay releases rocker 32 to co-operate with cam 39 to turn shaft 91, Fig. 4, anticlockwise so that pin 92 is in the path of pin 93 on wheel 96 which is driven with paper feed sprocket 46. Shaft 91 also causes pawl 88 to release a ratchet through cams which turn shaft 89 and the previously described mechanism, thus shaft 84 actuates to feed the paper until one of settable paper tabulation pins 93 hits rocker 92 turning shaft 91 to re-engage pawl 88 with the ratchet. Specifications 789,742, 798,093 [Group XL(a)] and 808,704 are referred to.